<html>
  <head><title>OK</title></head>
  <script>
    x.postMessage("from page");
    var handler2 = function(event) {
        x.postMessage("bouncing " + event.data);
    };
    var handler1 = function(event) {
        x.postMessage("bouncing " + event.data);
        x.removeEventListener("message", handler2);
    };
    x.addEventListener("message", handler1);
    x.addEventListener("message", handler2);
  </script>
<body>
</body>
</html>
